Mr. Dolphus Raymond lurched by on his thoroughbred.
There are no more uses of "thoroughbred" in the book.
Show samples from other sources
A feral hog, some hornets, and a prodigy led me through the woods so that I might stumble upon the first girl I ever kissed riding "TOC like he’s a thoroughbred next to the grave of an Austro-Hungarian Archduke.
John Green -- An Abundance of Katherines
There would be burnished, stick-legged Thoroughbreds, their jockeys in billowing bright silks, careering past.